Section 3: Shunting Signals

(Page 2 of 4)

The Great Western Railway had distinctive 'backing signals' with two holes in the arm [3.25 & 3.26]. When cleared, a backing signal indicated that the points were correctly set for a move over a line in the wrong direction. Once cleared, the signal could not be passed without verbal authority or a handsignal being given. The movement could then proceed as far as the line was clear. No more of these signals were installed after 1949.

An ordinary semaphore signal arm applies to train movements in only one direction. When viewed from the rear, the arm is coloured white and projects to the right of the post. The North Eastern Railway had some semaphore shunting signals that applied in both directions, with an arm coloured red on both sides. This was a rare example of a British semaphore signal whose indication was applicable to approaching movements even though the arm projected to the right of the post [3.31 & 3.32]. A different style of 'both ways' semaphore signal had been used on the Dornoch Light Railway to protect level crossings (see [16.7 & 16.8]).

In 1892, the Board of Trade declared that shunting signals should preferably be in the form of discs, as opposed to semaphore arms.

The recommendation in 1893 that white lights in fixed signals be dispensed with applied not only to main signals (see Section 2) but also to shunting signals. Accordingly, the LNWR began to gradually alter its shunting signals to show a green light when 'off' (see [3.2]).

From 1895, the Great Western Railway introduced its first independent shunting signals, in the form of small semaphores [3.33 & 3.34].

In 1898, the Glasgow & South Western Railway installed a number of shunting signals at Glasgow St. Enoch, which took the form of electrical 'banner' signals. These comprised a centrally pivoted arm, coloured red, inside a circular frame. When the arm was horizontal [3.35], the signal indicated 'stop', and when inclined through 45° (in either direction) [3.36], the signal indicated 'proceed'. Notably, these signals were illuminated during darkness and so gave the same indications by day or night.

Following its formation in 1899, the South Eastern & Chatham Railway began to replace the discs on its rotating shunting signals with little arms which resembled miniature semaphore signals. One arm was horizontal [3.37], and the other sloped downwards [3.38].

Around 1902, the LNWR altered its shunting signals to show a red light when 'on' (see [3.6]), instead of purple.

Concerns over the number of red signal lights visible to drivers at night led some companies to alter their shunting signals to display a white light in the 'on' position, instead of red. The GWR applied this change to its shunting signals [3.39] and backing signals [3.40] in 1904.

Some companies, such as the South Eastern & Chatham Railway, switched to using ground shunting signals in the form of miniature semaphores [3.41 & 3.42]. These had a white stripe on the arm, similar to a main stop signal.

In 1914, the railway companies agreed with the BoT that shunting signals reading from sidings or loops onto running lines should show a red light in the 'on' position. All other shunting signals could display a white light when 'on'. The new BoT 'Requirements' issued in the same year reflected that decision. The GWR adopted the policy of using a white light only if a signalled move could be made past the signal in the 'on' position.

To improve their visibility, the GWR began fitting its shunting signals with white 'disc' backgrounds from c.1914 [3.44 - 3.46]. Similar shunting signals were subsequently adopted as standard by the LNER, the LMS and the SR.

From c.1915, the LNWR began installing miniature semaphore signals (see [3.41 & 3.42]) as its standard form of shunting signal.

The resignalling of Victoria (Eastern) (South Eastern & Chatham Railway) in 1920 was the only scheme in Britain in which three-position shunting signals were used. These had a miniature semaphore arm depicted on a white disc. When the arm was horizontal (or a red light shown) [3.47], the meaning was 'stop'. Like their three-position main signal counterparts (see [2.76 & 2.77]), the arm could be worked to 45° or 90° in the upper quadrant, or a yellow or green light shown at night. With the arm at 45° (yellow light at night) [3.48], the meaning was the same as a two-position shunting signal in the 'off' position, i.e. "proceed as far as the line is clear, or to the next signal only". When the arm was vertical (green light at night) [3.49], the driver was given an assurance that the next signal was exhibiting a 'proceed' aspect and that the line was clear at least as far as that signal. The extra confidence this gave to drivers resulted in a speeding up of shunting operations.

The report of the IRSE's Three-Position Signalling Committee published in 1924 (see also Section 2) had suggested that ground shunting signals within three-aspect (or four-aspect) signalling areas should show either a white or a red light when 'on' and a green light when 'off'; however, it also recommended that shunting signals in these areas should preferably take the form of illuminated 'position' signals rather than colour lights.